Alignment features in a probing device

ABSTRACT

An image of an array of probes is searched for alignment features. The alignment features are then used to bring contact targets and the probes into contact with one another. The alignment features may be a feature of one or more of the tips of the probes. For example, such a feature may be a corner of one of the tips. An array of probes may be formed to have such alignment features.

FIELD OF THE INVENTION

This invention relates generally to probing a device.

BACKGROUND

Although the present invention is generally applicable to probing anydevice, the present invention is particularly suited for probing anintegrated circuit to test the integrated circuit. As is known,integrated circuits are typically manufactured as a plurality of dice ona semiconductor wafer. FIG. 1 illustrates a typical test system 100 fortesting a semiconductor wafer 124. The exemplary test system shown inFIG. 1, includes a tester 102, a test head 118, a probe card 106, and aprober 120.

A semiconductor wafer 124 is placed on a chuck (also commonly referredto as a stage) 114, which typically is capable of movement in the “x,”“y,” and “z” directions. The chuck 114 may also be capable of beingrotated and tilted and may be capable of other motions as well. Once thesemiconductor wafer 124 is placed on the chuck 114, the chuck istypically moved in the “x,” “y” directions so that terminals on the dice(not shown) of the wafer 124 align with probes 108 on the probe card106. The chuck 114 then typically moves the wafer 124 upward in the “z”direction, bringing the terminals into contact with the probes 108. Oneor more cameras 121, 122 may aid in aligning the terminals and theprobes and determining contact between the probes 108 and the terminals.

Once the terminals of the dice (not shown) are in contact with theprobes 108, a tester 102, which may be a computer, generates test data.The test data is communicated through one or more communication links104 to a test head 118. The test data is communicated from the test head118 through interconnections 116 (e.g., pogo pins) to the probe card 106and finally to the terminals of the dice (not shown) through probes 108.Response data generated by the dice are communicated in reversedirection from the probes 108, through the probe card 106, throughinterconnections 116, through the probe head 118, through acommunication link 104, to the tester 102.

Typically, the terminals on the dice and the probes 108 are relativelysmall. Regardless of the size of the terminals and probes, however,improved methods and techniques for aligning the terminals and theprobes are needed.

SUMMARY OF THE INVENTION

This invention relates generally to probing a device. An image of probesis searched for alignment features. The alignment features are then usedto bring contact targets and the probes into contact with one another.The alignment features may be a feature of one or more of the tips ofthe probes. For example, such a feature may be a corner of one of thetips.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary prior art semiconductor test system.

FIG. 2 illustrates an exemplary test system.

FIGS. 3A and 3B illustrate an exemplary probe card.

FIG. 4A illustrate a partial, side view of probe 382 in FIG. 3A.

FIG. 4B illustrate a partial, bottom view of probe 382 in FIG. 3A.

FIG. 4C illustrates an exemplary partial image of probe 382 in FIG. 3A.

FIG. 4D illustrates a partial, bottom view of contact structure 354 inFIGS. 4A and 4B.

FIG. 5 illustrates a partial, bottom view of probe 386 in FIG. 3A.

FIG. 6 illustrates a partial, bottom view of probe 384 in FIG. 3A.

FIG. 7 illustrates an exemplary process showing an exemplary use ofalignment features on probes.

FIG. 8 illustrates an image of the probe array of FIG. 3A.

FIG. 9 illustrates an exemplary method for making an exemplary probearray with alignment features.

FIGS. 10A through 12B illustrate an example of making a probe array withalignment features.

FIGS. 13A through 15B illustrate another example of making a probe arraywith alignment features.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

The present invention relates generally to probing a device. Thisspecification describes exemplary embodiments and applications of theinvention. The invention, however, is not limited to these exemplaryembodiments and applications or to the manner in which the exemplaryembodiments and applications operate or are described herein.

FIG. 2 illustrates an exemplary semiconductor test system 200, which insome respects may be generally similar to the test system 100 shown inFIG. 1. That is, exemplary test system 200 includes a tester 202, one ormore communication links 204, a prober 220, a test head 218, a probecard 206, and interconnections 216 between the probe card and the testhead, all of which may be in some instances generally similar to likeelements as described above with respect to FIG. 1. For conveniencepurposes (and not by way of limitation), directions in FIG. 2 areidentified using an “x,” “y,” and “z” coordinate system in which the “z”direction is the vertical (up or down) with respect to FIG. 2, the “x”direction is horizontally into or out of the page in FIG. 2, and the “y”direction is also horizontal but to the right or left in FIG. 2.

As shown in FIG. 2, the test system 200 also includes amicroprocessor-based controller 230. As shown, controller 230 includes adigital memory 232, a microprocessor 234, input/output electronics 236,and input/output port 238. The digital memory 232 may be any type ofmemory including an electronic memory, an optical memory, a magneticmemory, or some combination of the foregoing. As just two examples,digital memory 232 may be a read only memory, or digital memory 232 maybe a combination of a magnetic or optical disk and a random accessmemory. Microprocessor 234 executes instructions or “software” stored indigital memory 232, and input/output electronics 236 controls input andoutput of electrical signals into and out of controller 230. (As usedherein, the term “software” is intended to include any type of machineexecutable instructions including without limitation microcode andfirmware.) Input data and signals are received and output data andsignals are output via port 238. Various data may be input via port 238to controller 230. For example, such data may include data indicatingthe position or current movement status of chuck 214, images of theprobes 208 and/or wafer 224, etc. Among other things, control signalsfor controlling movement of the chuck assembly 214 may be output viaport 238 by controller 230.

Cameras 221 and 222 may, among other things, provide images of theprobes 208 and the wafer 224. As will be seen, those images may be usedto align terminals (not shown) on the wafer 224 with the probes 208. Aswill also be seen, software operating on controller 230 may, among otherthings, search an image of probes 208 for alignment features and movethe chuck 214 so that terminals (not shown) on the wafer 224 are broughtinto contact with the probes 208.

FIGS. 3A and 3B illustrate an exemplary probe card 306 that may be usedin test system 200. FIG. 3A shows a bottom view of the probe card 306,and FIG. 3B shows a side view. FIG. 3B also shows a partial-side view ofa wafer 324 being contacted by the probes of probe card 306. As will beseen, probe card 306 includes alignment features configured to bereliably discernable in an image of the probes.

The exemplary probe card 306 includes a board substrate 302 (e.g., aprinted circuit board) and a probe head 304 (e.g., a ceramic substrate).The board substrate 302 includes contacts 362 for contactinginterconnections 216 to test head 218 (see FIG. 2). Probes, each ofwhich includes body portion 352 and a contact structure 354, areattached to contacts 350 on the probe head 304. Internal and/or externalelectrical connections (not shown) connect ones of contacts 362 withones of contacts 350. Of course, the probe card 306 shown in FIGS. 3Aand 3B is exemplary only. Any type of probing contactor may be used,including without limitation a probe card assembly such as illustratedin U.S. Pat. No. 5,974,662, which is incorporated by reference herein inits entirety.

The exemplary probe card 306 shown in FIGS. 3A and 3B is configured tocontact four dice, each having eleven terminals in a lead-on-centerconfiguration. The probe card 306 thus has four sets of probes 308 a,308 b, 308 c, 308 d, each set for contacting one of the dice. (Thelocations of the four dice 324 a, 324 b, 324 c, 324 d relative to theprobes and locations of the eleven terminals 340 on each of the dice areshown in dashed lines in FIG. 3A.) Note, however, that each set ofprobes includes only nine probes. In some instances, it is not necessaryto contact all of the terminals of a die to test the die, and this isassumed to be the case in this example. Thus, for purposes of thisexample, it is assumed that only nine of the eleven terminals 340 needto be probed to test a die 324. Of course, the number of dice contactedat one time as well as the configuration of the terminals, the totalnumber of terminals, and the number of terminals actually contacted byprobes on each die is exemplary only. Any number of dice may becontacted at one time (including only one die or even less than onedie); the number and configuration of terminals on each die may vary;and the number of terminals per die that are actually contacted mayvary.

Because there are typically many more than four dice on a wafer, theprobe card 306 shown in FIG. 3A will test four dice, be repositioned tocontact and test four other dice, be repositioned again to contact andtest four other dice, etc. until all of the dice on the wafer have beentested. Dice 324 e and 324 f shown in FIG. 3B are other such dice thateither already have been tested or will subsequently be tested. Itshould be noted that probe cards are available that are capable oftesting many more than four dice at a time. Indeed, a probe card mayhave enough probes to contact and test all dice on a wafer at once. Fourdice are shown in FIG. 3A to simplify the illustration.

As will be seen, three probes in probe set 308 a (probes 382, 384, 386)and three probes in probe set 308 d (probes 388, 390, 392) includeexemplary alignment features configured to be discernible in an image ofthe probes. As will also be seen, the exemplary alignment feature oneach of probes 382 and 388 is one corner of the contact tip on theprobe, the exemplary alignment feature on each of probes 384 and 390 isfour corners of the contact tip, and the exemplary alignment feature oneach of probes 386 and 392 is two corners of the contact tip. Of course,the number of probe sets selected to have alignment features and thenumber of alignment features in each probe set is exemplary only. Threeprobes are selected in sets 308 a and 308 d of FIG. 3A for illustrationpurposes only.

FIGS. 4A and 4B shown partial side and partial bottom views,respectively, of exemplary probe 382. As shown, probe 382 includes abody portion 352 and a contact structure 354. One end of the bodyportion 352 is attached to a contact 350 of probe head 304 (see FIG.3B), and the contact structure 354 is attached to the other end of thebody portion 352. The contact structure 354 includes a support 456 and atip 458. The tip 458 is the part of the probe that makes actual contactwith a terminal on the wafer.

The tip 458, which includes four edges 460 a, 460 b, 460 c, 460 d andfour corners 462 a, 462 b, 462 c, 462 d, is disposed on what ispreferably a generally planar surface of the support 456. If a camera,such as camera 221 in prober 220 (see FIG. 2), is focused on the support456, an image of the probe will look generally as shown in FIG. 4C. Thesupport 456 will appear light. Angled surfaces of the tip 458 willappear dark, as will the background surface 490 of the probe head 304.Because the camera 221 is not focused on the probe body 352, it too willappear generally dark or at least darker than the support 456.

Many imaging processing algorithms are known for finding a particularfeature in an image, and such algorithms typically include design rulesspecifying minimum spacing requirements that, if followed, create arelatively high probability that the algorithm will find the feature inan image. As will be seen, support 456 is shaped and tip 458 ispositioned so that one corner 462 c of tip 458 meets the exemplaryminimum spacing requirements of a hypothetical image processingalgorithm. Such minimum spacing requirements are often referred to as“design rules.” The design rules specify minimum spacings for a featureso that the feature stands out in an image with sufficient contrast thatthe algorithm will reliably find the feature in the image. Put anotherway, the design rules are intended to ensure that a feature to be foundin an image is sufficiently surrounded by a differently coloredbackground such that an image processing algorithm can reliably find thefeature in the image. A feature formed in accordance with the designrules of an image search algorithm may be said to be “visible” in animage that includes the feature.

FIG. 4D, which shows a partial view of support 456 and tip 458 of probe382, illustrates an exemplary design rule for ensuring that one corner(in this case corner 462 c) can be found by a hypothetical image searchalgorithm in an image of probe 382, such as the image shown in FIG. 4C.Per the exemplary design rule illustrated in FIG. 4D, a corner is“visible” if the edges that form the corner are spaced a minimumdistance 472 from the outer perimeter of support 456 along a minimumlength 470 of the edges. As can be seen in FIG. 4D, two edges 460 a and460 d form corner 462 c. Although the entire length of edge 460 d is notspaced a distance 472 from an outer perimeter of support 456, a lengthof edge 460 d equal to or greater than length 470 is spaced a distance472 from the perimeter of support 456. As can also be seen, edge 460 aeasily meets the above-described design rule.

As can be seen corners 462 a, 462 b, and 462 d do not meet theabove-described design rules. That is, the edges that form each of thosecorners are not spaced for a length 470 from the corner a minimumdistance 472 from the perimeter of support 456. It should be noted thatcorners 462 a and 462 d are space from the perimeter of support 456 andthus may appear as distinct corner shapes in the image shown in FIG. 4C.There is, however, too little of the light colored support 456surrounding those corners to be sure that the hypothetical imagesearching algorithm will reliably find the corners, at least in thisexample.

Specific distances and lengths for 470 and 472 will depend on the actualimage processing algorithm used. As just one example, a distance of 10micrometers or greater for spacing 472 and a length of 10 micrometers orgreater for length 470 are believed to be sufficient for many knownimage processing algorithms. As another example, length 470 may be ⅓ thelength of an edge, and the length of an edge may be about 50micrometers. Such distances and lengths are exemplary only, however;smaller distances and lengths may be sufficient for particular imageprocessing algorithms.

FIG. 5 illustrates a partial bottom view of exemplary probe 386 (seeFIG. 3A). Exemplary probe 386 is generally similar to probe 382 shown inFIGS. 4A and 4B, except support 556 is shaped and tip 458 is positionedso that the above-described exemplary design rules are met for twocorners of the tip, namely corners 462 a and 462 b. Thus, two corners462 a and 462 b can reliably be found by the hypothetical imageprocessing algorithm.

FIG. 6 illustrates a partial bottom view of exemplary probe 384 (seeFIG. 3A). Exemplary probe 384 is generally similar to probes 382 and 386shown in FIGS. 4A, 4B, and 5, except support 656 is shaped and tip 458is positioned so that the above-described exemplary design rules are metfor all four corners 462 a, 462 b, 462 c, 462 d of the tip. Thus, allfour corners 462 a, 462 b, 462 c, and 462 d can reliably be found by thehypothetical image processing algorithm.

FIG. 7 illustrates an exemplary process in which alignment features,such as the exemplary alignment features shown in FIGS. 4A-6, areutilized to bring terminals of a semiconductor wafer into contact withprobes of a probe card. The process may be carried out in a test systemlike test system 200 and implemented in whole or in part by software ina microprocessor-based controller such as controller 230 (see FIG. 2).

As shown, FIG. 7 begins with obtaining a digital image (or images) ofthe probes at step 702. Equipment and processes for capturing anddigitizing an image are well known and need not be described here. Forexample, one or more cameras, such as camera 222, in prober 220 maycreate an image of the probes 208 of probe card 206. That image may bereceived by controller 230 via port 238. FIG. 8 illustrates an exemplaryimage of the probes of probe card 306 (FIG. 3A) captured by camera 222.

Referring again to FIG. 7, the image of the probes is then searched forone or more alignment features at step 704. Again, equipment andprocesses for searching an image for particular features are known, andany such equipment and process may be used. For example, computeralgorithms are known for finding a corner in an image. Such an algorithmmay search for a corner in the image by looking for two edges thatconverge to form generally a right angle. Such an algorithm may identifyan edge by looking for a contiguous portion of the image in which thereis a generally uniform and abrupt change from one color to another color(where “color” includes, but is not limited to, black and white in apurely binary image and various shades of gray in a purely gray scaleimage).

As mentioned above, step 704 may be implemented with a software-basedimage processing algorithm designed to find corners in an imageoperating in controller 230. (Such image processing algorithms are knownand need not be described here.) Typically, the number and type offeatures expected in the image is programmed into the algorithm. Asdiscussed above, probes 382 and 388 in FIG. 3A were configured such thatone corner of their tips is “visible”; probes 384 and 390 wereconfigured such that all four corners of their tips are “visible”; andprobes 386 and 392 were configured such that two of the corners of theirtips are “visible.” Thus, an image search algorithm operating oncontroller 230 might be programmed to find two sets of four corners,each forming a square or rectangle (each set corresponding to one ofprobes 384 or 390), two sets of two corners connected by a line segment(each set corresponding to one of probes 386 or 392), and two isolatedcorners (each corresponding to one of probes 382 or 388).

It should be noted, however, that it may be advantageous to program thealgorithm to search only for corners (rather than multiple cornersdisposed in a particular configuration, such as four corners of a squareor rectangle). This is because debris may build up on the tips of theprobes of a probe card, and such debris may obscure a corner of a tip.Thus, it may be advantageous for the image search algorithm to searchfor one corner even if multiple corners of a tip are configured to meetthe design rules of the algorithm and thus be reliably “visible” to thealgorithm. For example, probes are often designed to wipe across theterminals of the wafer. The wiping action can cause debris to build upon one side of the tips of the probes. Thus, it may be advantageous toconfigure the tips of such probes such that a corner located away fromwhere the debris is likely to build up (e.g., a corner on the tipopposite the direction of the wiping action) meets the design rules ofthe image search algorithm.

The step of finding the alignment features in the image (step 704) mayalso include determining a physical location of the points on the probesthat actually contact the terminals on the wafer. Data indicating thephysical location of the contact points from the alignment features maybe digitally stored, for example in controller 230, and utilized to makesuch calculations. For example, the actual point of contact with theterminals for the exemplary probe 382 illustrated in FIGS. 4A and 4B isthe truncated end of tip 458. Vector data indicating that the actualcontact point is a specified distance in a specified direction way fromthe corner may be stored in controller 230 and utilized by thecontroller to calculate the locations of the truncated ends of tips 458with respect to the corners found. The position of the truncated ends ofthe tips 458 thus can be calculated even if they are obscured by, forexample, debris build up.

Still referring to FIG. 7, the next step 706 is to bring terminals ofthe wafer 224 (or 324) into contact with the probes 208 (or 308 a, 308b, 308 c, 308 d). Equipment and methods for determining the positions ofterminals on a wafer are known, and any such equipment and method may beused. An example of such a known method is to create an image of all orpart of the wafer 224 (or 324) using camera 221. Image processingsoftware may then be used to find alignment features on the wafer. Inpractice natural features of the wafer are often utilized as alignmentfeatures. For example, a distinctive shape of a portion of theintegrated circuitry may be pre-correlated to positions of the terminalson the wafer, and images of the wafer searched for the distinctiveshape. Software operating on controller 230 may receive an image of thewafer (created, for example, by camera 221), search the wafer for thealignment features, and determine the locations of the terminals.

Using the now known positions of the probes (from step 704) and thepositions of the terminals, the chuck 214 moves the wafer 224 (or 324)such that the selected wafer terminals are brought into contact with theprobes, forming temporary electrical connections. Again, softwareoperating in controller 230 may issue commands to control movement ofthe chuck 214.

Although not shown in FIG. 7, once, the terminals are in contact withthe probes, the wafer dice on which the contacted terminals are locatedmay be tested. Thereafter, if necessary, the wafer may be repositionedsuch that terminals of different dice on the wafer are brought intocontact with the probes and those dice tested. This process ofcontacting terminals, testing dice, and repositioning the wafer tocontact and test other dice may continue until all the dice on the waferhave been tested.

FIG. 9 illustrates an exemplary method for making a probe array withalignment marks, such as the exemplary probe array shown in FIGS. 3A and3B. As shown in FIG. 9, the process begins with the step 902 of layingout locations for the probes. Typically, data identifying the number,locations, and signal assignments of terminals on dice to be tested isreceived, and the probes are laid out such that each probe is attachedto a contact 350 on a probe head 304 and oriented such that its contacttip corresponds to a location of a terminal 340 on a die to be tested(see FIG. 3B). Of course, the contact 350 on probe head 304 must berouted to a contact 362 on board substrate 302 that corresponds to thetype of signal the die terminal is to receive and/or output (see FIG.3B).

Referring again to FIG. 9, locations for alignment features in the probearray are determined at step 904. As should be apparent in FIGS. 3A and8, tips on some adjacent probes in the array may be so close to eachother that there is little to no room for an alignment feature that islikely to be distinguishable in a digital image (that is, no room for analignment feature that meets the design rules of an image searchingalgorithm to be used). In the exemplary probe layout shown in FIG. 3A,the outer probes 382 and 386 in probe set 308 a are selected to havealignment features. Probe 384 is also selected because of the presenceof extra space around the probe. Similar selections were made for probeset 308 d. In this example, no probes are selected in probe sets 308 bor 308 c because the six selected probes 382, 384, 386, 388, 390, 392 inprobe sets 308 a and 308 d provide a sufficient number of referencepoints to properly align the probes 308 a, 308 b, 308 c, 308 d withterminals 340.

It should be understood, however, that the number and pattern of probesselected in step 904 to have alignment features illustrated in FIGS. 3Aand 8 is exemplary only and selected to illustrate a variety of tipconfigurations. Any number and/or pattern of tips with distinguishablecorners may be used. For example, tips with distinguishable corners maybe placed on all of the probes. As another example, tips withdistinguishable corners may be placed on only two of the probes on theprobe substrate 304. As yet another example, tips with distinguishablecorners may be placed on two probes in each probe set 308 a, 308 b, 308c, 308 d. The foregoing exemplary patterns are not exhaustive; thepatterns are not critical, and any pattern may be selected.

Similarly, the selection shown in FIGS. 3A and 8 of two probes havingone “visible” corners, two probes having two “visible” corners, and twoprobes having four “visible” corners is exemplary only. In practice, allof the tips configured to function as an alignment mark may beconfigured to have the same number of “visible” corners. Alternatively,any combination of “visible” corner configurations may be used.

Referring again to FIG. 9, the next step 906 is to fabricate the probearray with the probes laid out as determined in step 902 and with thealignment marks as determined in step 904. FIGS. 10A-12B illustrate afirst example of step 906, and FIGS. 13A-15B illustrate a secondexample.

Turning first to FIGS. 10A-12B, those figures illustrate an example offabricating an array of probes in which contact structures 1160 a, 1160b (each comprising a support 1156 and a tip 1158) are separatelyfabricated and then attached to probe bodies 1252. For simplicity ofillustration, only two probes 1208 a, 1208 b in the array are shown inFIGS. 10A-12B. As will be seen, one of those probes 1208 a will befabricated with a an alignment mark, which will be one “visible” cornerof a tip 1158 a; the other probe 1208 b will not be fabricated with analignment mark.

FIGS. 10A-11B illustrate formation of contact structures 1160 a, 1160 bon a sacrificial substrate 1072, which may be a silicon wafer, forexample. As shown in FIGS. 10A and 10B, molds defining the shapes of thecontact structures are made on the sacrificial substrate 1072. In theexample shown in FIGS. 10A and 10B, the molds comprise pits 1058 a, 1058b and openings 1056 a, 1056 b. The pits 1058 a, 1058 b are etched in thesacrificial substrate 1072 and define the tips 1158 a, 1158 b of thecontact structures 1160 a, 1160 b to be formed. The openings 1056 a,1056 b are patterned in a layer of masking material 1074 deposited onthe sacrificial substrate 1072. The pits 1058 a, 1058 b and the openings1056 a, 1056 b may be formed in any suitable fashion. For example, thepits may be selectively etched through a mask using a solution such aspotassium hydroxide. The masking material 1074 may comprise photoresist.

Note that, in the example shown in FIGS. 10A and 10B, opening 1056 a ispatterned to provide sufficient space around one corner 1059 of pit 1058a such that the corresponding corner of the tip 1158 a formed in pit1058 a will be “visible” in an image of probe 1208 a. In this example,opening 1056 a and pit 1058 a are patterned and positioned to be similarto the exemplary support 456 and tip 458 shown in FIGS. 4A and 4B. Onthe other hand, the opening 1056 b is not patterned to providesufficient space around any of the corners of pit 1058 b to make any ofthe corners of tip 1158 b “visible” in an image of probe 1208 b.

As shown in FIGS. 11A and 11B, one or more materials are then depositedin the pits 1058 a, 1058 b and openings 1056 a, 1056 b to form contactstructures 1160 a, 1160 b, each comprising a tip 1158 a, 1158 b disposedon a support 1156 a, 1156 b. The material or materials may be any of anumber of structural materials including without limitation palladium,gold, rhodium, nickel, cobalt, silver, platinum, conductive nitrides,conductive carbides, tungsten, titanium, molybdenum, rhenium, indium,osmium, copper, and refractory metals; and alloys of any of theforegoing materials, including alloys comprising combinations of one ormore of the foregoing materials. Nonlimiting methods of depositing thematerial or materials include electroplating, chemical vapor deposition,physical vapor deposition, sputter deposition, electroless plating,electron beam deposition, and thermal evaporation.

It should be noted that other layers of material may be applied to thesacrificial substrate 1072 prior to applying the masking layer 1074. Forexample, a release layer (not shown) to facilitate release of thecontact structures 1160 a, 1160 b from the sacrificial substrate 1072may be applied; a seed or shorting layer (not shown) may be applied tofacilitate electroplating; a material (not shown) may be applied topromote adhesion of the contact structure material. Of course, one layerof material may serve more than one of the forgoing purposes. Also,additional materials may be applied to the contact structures 1160 a,1160 b.

Once contact structures 1160 a, 1160 b are formed on sacrificialsubstrate 1072 as shown in FIGS. 11A and 11B, the contact structures1160 a, 1160 b are attached to probe bodies 1252, which are themselvesattached to contacts 1250 on a probe head 1204. The contact structures1160 a, 1160 a may be attached to the probe bodies 1252 using anysuitable means, including soldering, brazing, and welding. The exemplaryprobe bodies 1252 shown in FIG. 12A comprise wires bonded at one end tocontacts 1250. (Note that FIG. 12A is not shown in cross-section.) Thewires may be made of a soft material and over coated with a hardermaterial as described in any of U.S. Pat. No. 5,476,211, U.S. Pat. No.5,917,707, U.S. Pat. No. 6,336,269, all of which are incorporated byreference herein in their entirety.

Alternatively, the probe bodies 1252 may be any type of probe, includingwithout limitation needle probes, buckling beams (e.g., “COBRA” probes),bumps, posts, and spring probes. Nonexclusive examples of spring probesthat may be used as probe bodies 1252 include, but are not limited to,probes described in U.S. Pat. No. 5,917,707; U.S. Pat. No. 6,268,015;U.S. Pat. No. 6,482,013; U.S. Pat. No. 5,974,662; U.S. PatentApplication Publication No. 2001/0001080; U.S. Patent ApplicationPublication No. 2001/0012739; and U.S. patent application Ser. No.09/953,666, filed Sep. 14, 2001 (pending). All of the foregoing U.S.patents and published and pending patent applications are incorporatedby reference herein in their entirety.

Additional examples and further discussion of forming contact structureson a sacrificial substrate and subsequently attaching the contactstructures to probe bodies can be found in U.S. Pat. No. 5,974,662, U.S.Pat. No. 6,441,315, and U.S. patent application Ser. No. 09/953,666,filed Sep. 14, 2001 (pending), all of which are incorporated byreference herein in their entirety.

As should be apparent, support 1156 a is shaped and tip 1158 a isdisposed on support 1156 a such that one corner of tip 1158 a will be“visible” in an image of probe 1208 a. Probe 1208 a thus includes analignment mark (i.e., the visible corner) and is generally similar toprobes 282 and 288 in FIG. 3A. Probe 1208 b, on the other hand, does notinclude an alignment mark because support 1156 b is not shaped and tip1158 b is not disposed on support 1156 b such that any of the corners oftip 1158 b will be reliably “visible” in an image of probe 1208 b. Itshould be apparent that two, three, or four of the corners of tip 1158 acould have been made “visible” by patterning opening 1156 a to define ashape for support 1156 a and positioning pit 1158 a to position tip 1158a on support 1156 a such that two corners of tip 1158 a are “visible”(e.g., as shown in FIG. 5), three corners of tip 1158 a are “visible,”or all four corners of tip 1158 a are “visible” (e.g., as shown in FIG.6). Of course, tip 1158 b could also have been formed such that one ormore corners of tip 1158 b are “visible.”

Turning next to FIGS. 13A-15B, those figures illustrate an example offabricating an array of probes in which tips are formed on beams 1456 a,1456 b. Again, for simplicity of illustration, only two probes 1508 a,1508 b in the array are shown in FIGS. 13A-15B. As will be seen, one ofthose probes 1508 a will be fabricated with an alignment mark, whichwill be four “visible” corners of a tip 1458 a; the other probe 1508 bwill not be fabricated with an alignment mark.

FIGS. 13A-14B illustrate formation of beams 1356 a, 1356 b on asacrificial substrate 1372. Generally speaking, the steps and materialsillustrated in FIGS. 13A-14B may be generally similar to the steps andmaterials illustrated and discussed above with respect to FIGS. 10A-12B,except that openings 1356 a, 1356 b in masking layer 1374 are shaped toform beams. For example, pits 1358 a, 1358 b may be generally similar topits 1058 a, 1058 b, and the material(s) deposited in openings 1356 a,1356 b (as shown in FIGS. 14A and 14B) may be generally similar to thematerial(s) deposited in openings 1056 a, 1056 b. Also, additionalmaterials (not shown), such as release, seed, and/or adhesion materials,may be deposited on the sacrificial substrate 1372 prior to forming themasking layer 1374 as discussed above with respect to FIGS. 10A-12B.

Note that, in the example shown in FIGS. 13A and 13B, opening 1356 a ispatterned to provide sufficient space around all four corners of pit1358 a such that the corresponding four corners of the tip 1458 a formedin pit 1358 a will be “visible” in an image of probe 1508 a. In thisexample, opening 1156 a and pit 1058 a are patterned and positioned tobe, in some respects, similar to the exemplary support 656 and tip 458shown in FIG. 6. On the other hand, the opening 1356 b is not patternedto provide sufficient space around any of the corners of pit 1358 b tomake the corners of the tip to be formed in pit 1358 b reliably“visible” in an image of probe 1508 b.

Once beams 1456 a, 1456 b are formed on sacrificial substrate 1372 asshown in FIGS. 14A and 14B, the beams 1460 a, 1460 b are attached topost structures 1580, which are themselves attached to contacts 1550 ona probe head 1504. The beams 1456 a, 1456 b may be attached to the poststructures 1580 using any suitable means, including soldering, brazing,and welding. The exemplary post structures 1580 shown in FIGS. 15A and15B comprise wires bonded at one end to contacts 1550. (Note that FIG.15A is not shown in cross-section.) The wires may be over coated asdescribed in U.S. Patent Application Publication No. 2001/0012739, whichis incorporated in its entirety herein by reference.

Post structures 1580 need not consist of two structures as shown inFIGS. 15A and 15B but may comprise one structure or more than twostructures. Moreover, post structures 1580 need not be wires but may beany type of structure suitable for supporting a beam. For example, poststructure 1580 may be a lithographically formed post as described inU.S. Pat. No. 6,268,015. As yet another exemplary variation, poststructures 1580, whether wires or other structures, may be formed on orattached to the beams 1456 a, 1456 b while the beams are still on thesacrificial substrate 1372 (see FIGS. 14A and 14B), after which theposts would be attached to contacts 1550 and the beams released from thesacrificial substrate. Many other variations with regard to the beamsare possible. For example, many different shapes and structures of theprobes are possible by, for example, shaping the masking layer 1274and/or utilizing a plurality of masking layers 1274. Examples of theforegoing can be found in U.S. Pat. No. 6,482,013, U.S. Pat. No.6,184,053, U.S. Pat. No. 6,268,015, U.S. Patent Application PublicationNo. 2001/0001080, U.S. patent application Ser. No. 09/539,287, filedMar. 30, 1999 (pending), all of which are incorporated by referenceherein in their entirety.

As should be apparent, beam 1456 a is shaped and tip 1458 a is disposedon beam 1456 a such that all four corners of tip 1458 a will be“visible” in an image of probe 1508 a. Probe 1508 a thus includes analignment mark (i.e., the “visible” corners). Probe 1508 b, on the otherhand, does not include an alignment mark because beam 1456 b is notshaped and its tip (not shown) is not disposed on beam 1456 b such thatany of the corners of the tip will be “visible” in an image of probe1508 b. It should be apparent that one, two, or three of the corners oftip 1458 a could have been made “visible” by patterning opening 1456 ato define beam 1456 a and positioning pit 1358 a to position tip 1458 aon beam 1456 a such that only one corner of tip 1458 a is “visible”(e.g., as shown in FIGS. 4A, 4B, and 4D), two corners of tip 1458 a are“visible” (e.g., as shown in FIG. 5), or three corners of the tip 1458 aare “visible.” Of course, the tip (not shown) on beam 1456 b could alsohave been formed such that one or more corners of its tip are “visible.”

It should be noted that the figures are not necessarily to scale. Forexample, the probes shown in FIGS. 3A and 3B would typically be muchsmaller compared to the probe head 304 and the board substrate 302.Likewise, the dice 324 b, 324 d, 324 e, and 324 f would typically bemuch closer together on wafer 324 than shown in FIG. 3B. The probes areshown bigger and the dice spaced farther apart in FIGS. 3A and 3B forillustration purposes. Other figures may be similarly not to scale.

Although the principles of the present invention have been illustratedand explained in the context of specific embodiments, it will beappreciated by those having skill in the art that various modificationscan be made to the disclosed embodiments without departing from theprinciples of the invention.

For example, although the foregoing exemplary embodiments showapplication of the invention to a prober for probing semiconductorwafers, the invention is equally applicable to any testing of anelectronic device in which probes are brought into contact withterminals or other contact points or features on the electronic devicefor the purpose of testing the electronic device. Examples of theforegoing include sockets and test probes for packaged or unpackagedsemiconductor devices, including singulated semiconductor dice. Indeed,the invention is applicable to any application in which any type ofprobes are aligned with contact points or contact features of any typeof device.

As yet another example, although FIGS. 10A-15B show formation of atleast a portion of the probes on a sacrificial substrate, probes canalternatively be formed in whole or in part directly on the probesubstrate 304, 1204, 1504. Examples are described in U.S. Pat. No.6,268,015, which is incorporated by reference herein in its entirety. Asyet another alternative, pieces of the probes can be formed in multiplesteps on multiple sacrificial substrates, as described in U.S. Pat. No.6,520,778, which is incorporated by reference herein in its entirety.

As still another example, although controller 230 is described asmicroprocessor based and operating under software control, controller230 may be replaced with a manual controller that is manuallymanipulated by an operator. For example, an operator might manuallysearch an image and then manually move the chuck 214. Alternatively,controller 230 may operate in part automatically and in part manually.Of course, controller 230 may be replaced with a controller that is notmicroprocessor based or a controller that is only partiallymicroprocessor based.

Other examples of variations include without limitation utilizingcorners of features on the probes other than tips as alignment marks;placing alignment features on dummy probes (that is, probes that are notconfigured to make contact with a wafer terminal) or on platforms orsupports other than probes.

1. A probing apparatus comprising: a substrate; and a plurality ofprobes disposed on said substrate, each of said probes comprising acontact tip, said tips disposed in a pattern to contact terminals ofsemiconductor dies to be tested, wherein two or more of first probes ofsaid plurality of probes each comprise a first tip disposed on a firstsubstantially flat surface of said first probe, said first tip disposedon said first substantially flat surface such that a corner of saidfirst tip is disposed at least a predetermined distance from a perimeterof said first substantially flat surface, wherein said predetermineddistance is a minimum spacing for a processing algorithm to find saidcorner of said first tip in a digital image that includes portions of atleast some of said probes, and one or more of second probes of saidplurality of probes each comprising a second tip disposed on a secondsubstantially flat surface of said second probe, said second tipdisposed on said second substantially flat surface such that all cornersof said second tip are disposed less than said predetermined distancefrom a perimeter of said second substantially flat surface.
 2. Theprobing apparatus of claim 1, wherein said first tip of each of saidfirst probes is disposed on said first substantially flat surface ofsaid first probe such that a plurality of corners of said first tip areeach disposed at least said predetermined distance from said perimeterof said first substantially flat surface.
 3. The probing apparatus ofclaim 2, wherein said predetermined distance is 10 microns.
 4. Theprobing apparatus of claim 2, wherein said first tip of each of saidfirst probes is disposed on said first substantially flat surface ofsaid first probe such that four of said corners of said first tip areeach disposed at least said predetermined distance from said perimeterof said first substantially flat surface.
 5. The probing apparatus ofclaim 1, wherein: each of said first probes comprises a first bodycoupled at a first end of said first body to said substrate, said firstbody extending away from said substrate to a second end of said firstbody, said first substantially flat surface comprising a first side of afirst support structure, a second opposite side of said first supportstructure coupled to said second end of said first body; and each ofsaid second probes comprises a second body coupled at a first end ofsaid second body to said substrate, said second body extending away fromsaid substrate to a second end of said second body, said secondsubstantially flat surface comprising a first side of a second supportstructure, a second opposite side of said second support structurecoupled to said second end of said second body.
 6. The probing apparatusof claim 5, wherein said predetermined distance is 10 microns.
 7. Theprobing apparatus of claim 1, wherein said corner of said first tipcomprises converging edges of said tip, and at least ⅓ of a length ofeach of said converging edges from said corner is disposed saidpredetermined distance from said perimeter of said first substantiallyflat surface.
 8. The probing apparatus of claim 7, wherein saidpredetermined distance is 10 microns.
 9. The probing apparatus of claim1, wherein said probing apparatus is a probe card assembly for use in atest system for testing dies of a semiconductor wafer.
 10. The probingapparatus of claim 9, wherein said predetermined distance is 10 microns.11. The probing apparatus of claim 1, wherein said predetermineddistance is 10 microns.